1. Field of the Invention
The present invention relates to a sheet-decorating injection molding machine capable of simultaneously forming a resin molding and a decorative pattern on a surface of the resin molding in a mold by injection molding. More particularly, the present invention relates to a sheet-decorating injection molding machine capable of laminating a decorative sheet printed with patterns, letters and/or the like to a surface of a resin molding formed by injection molding for decoration.
2. Description of the Related Art
Various sheet-decorating injection molding methods, which simultaneously carries out forming a resin molding by injection molding and laminating a decorative sheet to a surface of the resin molding, have been proposed. Most of those known sheet-decorating injection molding methods comprises all or some of the following steps (a) to (i). These steps are performed sequentially or some of the steps are performed simultaneously or in parallel to each other (Refer to JU-B No. 3-56344 and JP-B Nos. 50-19132 and 7-41637).
(a) A sheet feeding step of feeding a decorative sheet onto the parting surface of the female mold of a mold for injection molding; PA1 (b) A sheet holding step of fixedly holding a decorative sheet on the parting surface of the female mold; PA1 (c) A sheet softening step of softening the decorative sheet by heating the decorative sheet with a heating plate or the like; PA1 (d) A sheet drawing step of drawing the decorative sheet by suction and/or pneumatic pressing so that the decorative sheet conform to a surface defining a hollow in the female mold; PA1 (e) A mold clamping step of moving the female mold toward the male mold of the mold or moving the male mold toward the female mold (the female mold is moved toward the male mold in most cases) to close and clamp the mold; PA1 (f) An injection molding step of injecting a fluidic resin (molten resin) through the male mold in to a cavity defined by the male and the female mold and solidifying the resin in the cavity; PA1 (g) A mold opening step of separating the female mold and the male mold from each other to open the mold; PA1 (h) A sheet trimming step of severing marginal portions of the decorative sheet from a portion of the decorative sheet to be attached to a molding formed by injection molding; and PA1 (i) An ejecting step of ejecting a sheet-decorated molding (product) decorated by the decorative sheet from the female or the male mold.
The simultaneous performance of the plurality of steps signifies the performance of the plurality of steps in a single process. More specifically, the decorative sheet is fixedly held between the male and the female mold in the mold clamping process (e) to carry out the sheet holding step (b) and the mold clamping step (e) simultaneously, or the decorative sheet is drawn by the heat and pressure of the molten resin in the injection molding step (f) to carry out the sheet drawing step (d) and the injection molding step (f) simultaneously.
A laminate decorative sheet or a transfer decorative sheet is used as the decorative sheet depending on the type of the product. When a laminate decorative sheet is used, the laminate decorative sheet is incorporated entirely into a molding during injection molding to form a decorative layer on the surface of the molding. When a transfer decorative sheet is used as the decorative sheet, the base sheet of the transfer decorative sheet incorporated into the surface of a molding is peeled off to leave a transfer layer on the molding to form a decorative layer.